src/main/rx/pwm.c

   1 /*
   2  * This file is part of Cleanflight.
   3  *
   4  * Cleanflight is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * Cleanflight is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with Cleanflight.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include <stdbool.h>
  19 #include <stdint.h>
  20 #include <stdlib.h>
  21
  22 #include <string.h>
  23
  24 #include "platform.h"
  25
  26 #if defined(USE_RX_PPM)
  27
  28 #include "build/debug.h"
  29 #include "common/utils.h"
  30
  31 #include "config/feature.h"
  32
  33 #include "drivers/timer.h"
  34 #include "drivers/rx_pwm.h"
  35 #include "drivers/time.h"
  36
  37 #include "fc/config.h"
  38
  39 #include "rx/rx.h"
  40 #include "rx/pwm.h"
  41
  42 #define RC_PWM_50HZ_UPDATE          (20 * 1000)     // 50Hz update rate period
  43
  44 static uint16_t channelData[MAX_SUPPORTED_RC_PPM_CHANNEL_COUNT];
  45
  46 static uint16_t readRawRC(const rxRuntimeConfig_t *rxRuntimeConfig, uint8_t channel)
  47 {
  48     UNUSED(rxRuntimeConfig);
  49     return channelData[channel];
  50 }
  51
  52 static uint8_t ppmFrameStatus(rxRuntimeConfig_t *rxRuntimeConfig)
  53 {
  54     UNUSED(rxRuntimeConfig);
  55
  56     // PPM receiver counts received frames so we actually know if new data is available
  57     if (isPPMDataBeingReceived()) {
  58         for (int channel = 0; channel < MAX_SUPPORTED_RC_PPM_CHANNEL_COUNT; channel++) {
  59             channelData[channel] = ppmRead(channel);
  60         }
  61
  62         resetPPMDataReceivedState();
  63         return RX_FRAME_COMPLETE;
  64     }
  65
  66     return RX_FRAME_PENDING;
  67 }
  68
  69 bool rxPpmInit(rxRuntimeConfig_t *rxRuntimeConfig)
  70 {
  71     const timerHardware_t * timHw = timerGetByUsageFlag(TIM_USE_PPM);
  72
  73     if (timHw == NULL) {
  74         return false;
  75     }
  76
  77     if (!ppmInConfig(timHw)) {
  78         return false;
  79     }
  80
  81     rxRuntimeConfig->rxRefreshRate = RC_PWM_50HZ_UPDATE;
  82     rxRuntimeConfig->requireFiltering = true;
  83     rxRuntimeConfig->channelCount = MAX_SUPPORTED_RC_PPM_CHANNEL_COUNT;
  84     rxRuntimeConfig->rcReadRawFn = readRawRC;
  85     rxRuntimeConfig->rcFrameStatusFn = ppmFrameStatus;
  86
  87     return true;
  88 }
  89 #endif
  90